Chief diplomats of Germany, France, Russia, and Ukraine will meet on November 6 in Berlin to agree on the next steps in ending the Ukraine conflict, a German Foreign Ministry spokeswoman said.

Heavy weapons withdrawal is one possible measure that could be considered, with the recent progress on withdrawal of small-caliber artillery and mortars serving as a model, Sawsan Chebli said November 4.

A cease-fire between Ukrainian government troops and pro-Russian separatists has largely been kept since September, despite sporadic outbreaks of violence, and there have been exchanges of prisoners, said Ertugrul Apakan, head monitor at the Organization for Security and Co-operation in Europe (OSCE).

He said demining eastern Ukraine might be another key step to take. OSCE observers would define and map priority areas for removing mines, he said.

"The cease-fire can only be sustainable if we make progress towards a political solution for the conflict," Chebli said, including enacting constitutional reform in Ukraine and ensuring unfettered access of OSCE monitors to the entire conflict region.